Converting mono audio signals to stereo is a common need in current audio electronics. Two channel stereo sound is now standard. Two channel stereo generally has a much more natural and pleasant quality than mono. People naturally hear everyday sounds in stereo. There are still situations where mono sound signals exist such as telephone conversations, old recordings, low-end toys and radios etc. Converting such signals to stereo can greatly enhance their naturalness.
A mono signal carries no directional clues to the original location of the recorded sources. Additionally the original sound should be modified as little as possible to avoid coloration. Since mono signals are more common in low-end equipment, the computational cost of the mono to stereo conversion should be at a minimum because the low-end equipment typically has limited computational capacity.